Author Topic: cutback style control arm fatigue cracks  (Read 348 times)

Offline Stangly

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cutback style control arm fatigue cracks
« on: March 25, 2017, 02:49:19 PM »
I have a pair of rust free UCA that are of the cutback style, Mid June build Date 68 San Jose car. Both arms have half inch long fatigue cracks as discussed in some older threads at the area cut out near the ball joint. The cracks are on each side of the ball joint towards the closest bolt hole and thru the section of metal. This is consistent with both arms. Both arms had four waffled rivets so I believe them to be original to the car. I found the letter K on one and the number 4 on the other stamped on the top of the ball joint end. Can these cracks be welded/repaired by a qualified welder. The car is being restored as an occasional driver and I am concerned about the integrity of the repaired part. Any input would be greatly appreciated.

Thanks,
69 Sports Roof 302 2V (numbers matching)
Dearborn (June build date) Acapulco Blue
68 Coupe J-Code
San Jose (June build date) Sea Foam Green
2001 V6 Laser Red
2015 GT Deep Impact Blue

Offline Bob Gaines

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Re: cutback style control arm fatigue cracks
« Reply #1 on: March 25, 2017, 02:59:20 PM »
I have a pair of rust free UCA that are of the cutback style, Mid June build Date 68 San Jose car. Both arms have half inch long fatigue cracks as discussed in some older threads at the area cut out near the ball joint. The cracks are on each side of the ball joint towards the closest bolt hole and thru the section of metal. This is consistent with both arms. Both arms had four waffled rivets so I believe them to be original to the car. I found the letter K on one and the number 4 on the other stamped on the top of the ball joint end. Can these cracks be welded/repaired by a qualified welder. The car is being restored as an occasional driver and I am concerned about the integrity of the repaired part. Any input would be greatly appreciated.

Thanks,
It is most logical to replace them with other like cut back arms . I suppose they could be welded but how are they going to look and what effort to weld them and dress them out presentable is a question to ask yourself compared to what other nice cores may cost. If you feel that you have to have them on occasional driver car replace them with like arms and wait for those to crack too. Maybe they will and maybe not. Of course you could always go with  the stronger UCA used in production before or after the cutback design. There are far more of those around compared to the weaker cut back design. 
Bob Gaines,Shelby enthusiast, Shelby collector , Shelby concours judge SAAC,MCA,Mid America Shelby

Offline azscj

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Re: cutback style control arm fatigue cracks
« Reply #2 on: March 25, 2017, 08:36:04 PM »
I see this issue all the time on the cutback control arms.  They can be repaired (welded and ground down again) but its a bit of a process.  I would say that more than 50% of the control arms like this I see have those exact same cracks. 
Marcus Anghel
MCA National Gold Card Judge, 69-71 Mustang
SAAC National Head Judge, Boss Mustangs

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Offline Stangly

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Re: cutback style control arm fatigue cracks
« Reply #3 on: March 26, 2017, 07:44:29 PM »
Thanks for input guys, I have two more sets to check for condition and style hopefully I can scrounge a descent pair.
69 Sports Roof 302 2V (numbers matching)
Dearborn (June build date) Acapulco Blue
68 Coupe J-Code
San Jose (June build date) Sea Foam Green
2001 V6 Laser Red
2015 GT Deep Impact Blue